Unit 4 - Lesson 9: Electromagnetic Induction Flashcards
When moving a wire (or any conductor) through a magnetic field, what is induced in the wire?
Moving a wire (or any conductor) through a magnetic field induces a voltage in the wire.
How does current move in a complete circuit?
It flows.
What is electromagnetic induction?
Electromagnetic induction can create a voltage by movement of a conductor in a magnetic field.
I.E. Moving a wire (or any conductor) through a magnetic field induces a voltage in the wire.
Example: Moving a magnet inside a coil of wire produces the same effect: inducing voltage in the wire.
Motors use electricity to create movement. Generators use movement to create electricity. How do they do this?
They do this by electromagnetic induction.
How do we increase the voltage induced by electromagnetic induction?
By moving the magnet faster, using a stronger magnet, or wrapping the wire into a coil.
How can we change the direction of the current during electromagnetic induction?
By moving the wire or magnet. An alternating current is produced when a wire moves through a magnetic field (or when a magnetic field moves through a wire). The changing magnetic field changes the direction of the current. An ammeter would shift from positive to negative amps.
AC GENERATORS \/
AC GENERATORS \/
If you rotate a loop of wire between two magnets, what is induced into the wire?
Voltage.
Rotating a loop of wire between two magnets induces a voltage in the wire. What happens to the current at every half rotation of the loop of wire/coil?
The current switches direction at every half rotation of the loop of wire/coil.
Rotating a loop of wire between two magnets induces a voltage in the wire. Every half rotation, the current switches direction. What kind of current does this generate?
An alternating current.
What apparatus prevent the wires from getting tangled?
Slip rings. Each side of the loop is attached to its own slip ring.
What apparatus let the slip rings rotate whilst maintaining the circuit?
Carbon Brushes.
What has to be in contact to make the current higher?
The current is higher when the WIRE is in contact with more of the MAGNETIC FIELD.
When the coil/loop rotates on to its side, what will the current decrease or increase to?
It will decrease to zero.
When the coil/loop rotates to be flat, will the current be at its highest or at its lowest?
When flat, the current will be highest.
What uses AC generators? How is the turning action created for this thing?
Power stations (like coal and nuclear) use AC generators. The turning action is created by turbines.
Draw an AC generator diagram.
https://i.pinimg.com/736x/34/a7/d1/34a7d1ac467889b022ce2051a758f068.jpg
Draw a graph that represents how the coil position effects the current.
https://i.pinimg.com/736x/b9/09/4e/b9094e910df58344a7fc2b40bb98ca25.jpg
DC GENERATORS \/
DC GENERATORS \/
What are small, basic generators that produce DC (direct current) sometimes called?
Dynamos
We can place a loop of wire in a magnetic field to induce a voltage. As the current will naturally be alternating, what apparatus do we need to use to produce DC (direct current)?
We need to use a split ring commutator to produce direct current. This reverses the current every half rotation of the loop.
We can place a loop of wire in a magnetic field to induce a voltage. As the current will naturally be alternating, we need to use a split ring commutator to produce direct current. What can we do alternatively to produce DC?
Alternatively, we can place a rotating magnet inside a loop of wire. This turning wheel rotates a magnet inside a coil of wire. This generates a current in the wire.
How do you increase the induced voltage in a DC generator?
To get a larger voltage we can:
- Increase the magnetic field (use stronger magnets)
- Increase the number of turns on the wire
- Increase the speed of movement
Draw a diagram of a rotating magnet being used to produce DC in a generator instead of a split ring commutator.
https://i.pinimg.com/736x/1e/16/92/1e169293fa3cf2783788b974e61fcfa4.jpg
